什麼是 Vuex?

Vuex 是 Vue 應用程式的狀態管理，組件常會跨結構的傳遞狀態、需要全域狀態的管理，用 Vuex 可以更容易的控管你的資料流。

沒有用Vuex

使用Vuex

Vuex 的前置作業

store/index.js

import { createStore } from "vuex";

export default createStore({
  state: {},
  actions: {},
  mutations: {},
  modules: {},
});

main.js

import { createApp } from "vue";
import App from "./App.vue";
import store from "./store";

createApp(App)
  .use(store) // 使用store
  .mount("#app");

State Getters Mutations Actions

State:
🔸 存放資料狀態

Getters:
🔸 取得狀態，類似 computed 重組資料
🔸 components 不要直接取得 state，先用 getters 去處理資料邏輯，再回傳資料。

Mutations:
🔸 唯一改變 state 的方法
🔸 只能做同步操作，mutations 不能做非同步操作
🔸 mutations 需用 commit 呼叫

Actions:
🔸 actions 觸發 mutations，commit 會發送事件給 mutations
🔸 actions 才做非同步操作
🔸 需用 dispatch 呼叫
🔸 不能更改 state

流程: components ➜ dispatch ➜ actions ➜ commit ➜ mutations ➜ state ➜ getters ➜ components

Vuex 範例

側邊選單收合

App.vue

import MenuBtn from "../src/components/MenuBtn.vue";
import MenuSlid from "../src/components/MenuSlid.vue";
export default {
  components: {
    MenuBtn,
    MenuSlid,
  },
  setup() {
    return {};
  },
};

<div id="app">
  <MenuBtn />
  <div class="content">
    <img id="img" alt="Vue logo" src="./assets/logo.png" />
  </div>
  <MenuSlid />
</div>

* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}
html,
body {
  width: 100%;
  height: 100%;
  font-family: "Microsoft JhengHei", "Heiti TC", "sans-serif";
}
#img {
  display: block;
}
#app {
  position: relative;
  width: 100%;
  height: 100%;
  > .content {
    width: 100%;
    height: 100%;
    background-image: url("https://source.unsplash.com/WLUHO9A_xik/1600x900");
    background-size: cover;
    background-position: center;
    display: flex;
    justify-content: center;
    align-items: center;
  }
}

store/index.js

import { createStore } from "vuex";

export default createStore({
  state: {
    isOpen: false,
  },
  // actions觸發mutations，commit會發送事件給mutations
  actions: {
    handMenuOpen(context) {
      // context.state等於store的state
      const openBool = !context.state.isOpen;
      // 傳入openBool參數給mutations
      context.commit('handOpenState', openBool);
    }
  },
  // 只有mutations可以修改state
  mutations: {
    // 接收actions給的參數openBool，再去改變state的值
    handOpenState(state, openBool) {
      state.isOpen = openBool;
    }
  },
  // 類似computed重組資料，不要直接取得state，先用getters去處理資料邏輯，再回傳資料
  getters: {
    isOpen(state) {
      return state.isOpen;
    }
  },
});

MenuSlid.vue

import { computed } from 'vue';
import { useStore } from "vuex"; // 所有跟vuex有關的內容
export default {
  setup() {
    const store = useStore();
    // 用computed取得isOpen資料，不要把整個store return出來
    const isOpen = computed(()=>{
      return store.getters.isOpen
    })
    const handClickMenu = () => {
      store.dispatch('handMenuOpen');
    };
    return { handClickMenu, isOpen };
  },
};

<div :class="['menu', {open: isOpen} ]">
  <a class="closeBtn" @click="handClickMenu">
    <i class="fas fa-times fa-3x"></i>
  </a>
  <ul class="nav">
    <li><a>abous</a></li>
    <li><a>content</a></li>
    <li><a>user</a></li>
    <li><a>address</a></li>
  </ul>
</div>

MenuBtn.vue

import { useStore } from "vuex";
const store = useStore();
export default {
  setup() {
    const store = useStore();
    // 用dispatch觸發一個事件到actions
    const handClickMenu = () => {
      store.dispatch('handMenuOpen');
    };

    return { handClickMenu };
  },
};

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<a class="menuBtn" @click="handClickMenu">
  <i class="fas fa-bars fa-3x"></i>
</a>

a.menuBtn {
  cursor: pointer;
  position: absolute;
  color: #fff;
  z-index: 10;
  top: 50px;
  right: 50px;
}

Vuex 結構拆分

當 Vuex 內容越來越多時，可以拆分檔案，比較好管理

store/index.js

import { createStore } from "vuex";
import state from './state.js';
import actions from './actions.js';
import mutations from './mutations.js';
import getters from './getters.js';

export default createStore({
  state, actions, mutations, getters
});

store/state.js

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export default {
  isOpen: false,
}

store/getters.js

export default {
  isOpen(state) {
    return state.isOpen;
  }
}

store/mutations.js

export default {
  handOpenState(state, openBool) {
    state.isOpen = openBool;
  }
}

store/actions.js

export default {
  handMenuOpen(context) {
    const openBool = !context.state.isOpen;
    context.commit('handOpenState', openBool);
  }
}

Vuex modules

module可以依照功能來區分資料
設定namespaced在不同的modules可以有一樣的名稱，依照modules名稱做判斷

store/Auth/index.js

export default {
  namespaced: true,
  state: {
    token: '',
  },
  actions: {
    handSetToken(context, token) {
      context.commit('setToken', token);
    }
  },
  mutations: {
    setToken(state, token) {
      state.token = token;
    }
  },
  getters: {
    getToken(state) {
      return state.token;
    }
  }
}

App.vue

import { onMounted } from 'vue';
import { useStore } from 'vuex';
export default {
  setup() {
    const store = useStore();
    onMounted(() => {
      // 因為設定namespaced，前面要加modules名稱Auth/
      store.dispatch('Auth/handSetToken', 'aaa');
      console.log(store.getters['Auth/getToken']);
    })
    return {};
  },
};